The sidewalls of a tire are the lateral portions of the tire that connect a tread, intended to come into contact with the ground, to two beads, intended to be mounted on a rim.
It is known that a bicycle tire can cooperate with an electrical device, such as an electric generator device, for supplying the lights of the bicycle on which it is mounted.
An electric generator device, for the lights of a bicycle, which is intended to cooperate with a tire has been described in particular in documents DE-4011567-A1 and U.S. Pat. No. 5,165,776. Such a tire comprises a continuous toothing with a radial generatrix, said toothing being positioned circumferentially on a sidewall of the tire and being intended to cooperate with a complementary toothing on a pinion of the electric generator device. The toothing positioned on the tire sidewall is designed to rotate the free pinion of the electric generator device.
It is also known that a bicycle tire must be visually detectable at night in order to meet regulatory requirements.
With regard to the visual detection of an object in a dark environment, it is conventional to use a retroreflective device, which is a passive system based on the application of the optical system known as reflector and is intended to indicate an object at night or in darkness. Retroreflection is the name given to reflection in which the light rays are reflected in a direction similar to that from which they come, this property being maintained in spite of wide variations in the direction of incident rays. A retroreflective device is the name given to a device which, when irradiated directionally, retroreflects a relatively large proportion of the incident rays.
In order to visually detect a tire, retroreflective covering materials are generally incorporated into the sidewalls of the tire, in particular in the case of a tire for a two-wheeled vehicle. Agreement addendum 87 to UN regulation 88 of 20 Mar. 1958 concerning the adoption of uniform conditions of approval and reciprocal recognition of approval of motor vehicle equipment and parts defines the uniform provisions concerning the approval of retroreflective tires for two-wheeled vehicles. Within the meaning of the abovementioned regulation 88, a retroreflective tire is a tire ready for use comprising a retroreflective circle incorporated into each of the sidewalls of the tire. This retroreflective circle is often an adhesive retroreflective strip.
Through the materials and shapes used for a retroreflective device, manufacturers are looking for the best light reflection index, limiting losses of intensity through diffusion or absorption into the material. The basic materials are varied and adapted to the various uses. By way of example and in a non-exhaustive manner, the marketplace includes adhesive tapes, technical fabrics, paints, and coating products based on glass microbeads acting as reflective pigment. In the case of a bicycle tire, an adhesive retroreflective strip is frequently used.
Therefore, in order to fulfil the two above-described functions of cooperation with an electrical device and visual detection, respectively, it is necessary to be able to position, on a tire sidewall with a limited section height, both a continuous toothing and a retroreflective strip, while ensuring that the corresponding functions are correctly fulfilled.